This disclosure relates generally to fluid dispensing. More particularly, this disclosure relates to dispensing meters.
Automotive fluids, such as antifreeze, transmission fluid, and engine oil, are typically dispensed from bulk containers. For example, automotive service stations typically dispense small amounts of engine oil from a large drum using a handheld meter. The handheld meter receives fluid from the bulk storage drum and dispenses a desired volume of the fluid at a desired location. The user can use the user interface of the handheld meter to communicate with a central fluid monitoring computer to track and record the volume of fluid dispensed from the bulk containers. In current handheld meters, the user interface includes a button elevated above the handle, such that users typically set the handheld meter on the ground prior to inputting information. In addition, the display screen is susceptible to damage if the handheld meter is dropped or otherwise collides with an object.
A valve is disposed within the handheld meter and controls the flow of fluid through the device. The valve can be controlled by a trigger. The valve can be a manual valve, controlled on and off by a manual trigger; a pre-set metered valve, which includes a manual trigger but the valve automatically closes after a pre-set volume of fluid has been dispensed; or a metered valve, where the trigger cannot activate the valve until the handheld meter receives a dispense authorization. When the valve is initially activated, a control seal can shift into the fluid inlet, where high-velocity fluid impingement can cause the control seal to become displaced and unseated. When the valve closes, the control seal can experience scarfing when the control seal encounters a sharp edge geometry. Scarfing most commonly occurs when the valve is quickly modulated between slightly-open and slightly-closed positions, such as when the user is topping off the fluid at the end of a fluid dispense event. The valve also includes a top dynamic seal that can have minor leaking during valve reciprocation. The minor leakage can occur due to seal cross-sectional rotation due to valve reciprocation and because the top dynamic seal is always experiencing fluid pressure. In addition, the top dynamic seal contacts the cast housing of the handheld meter and can experience leakage due to the porosity of the cast housing.
Dynamic pressure forces can also exert a higher force on an upper portion of the valve than the lower portion of the valve, which can overcome the spring force that shifts the valve to the closed position. The valve can thus become stuck in the open position due to pressure imbalances within the valve chamber.
To replace the valve, the trigger is removed from the trigger control mechanism. The electronics bezel housing must be removed to provide access to the trigger mechanism pivot point. As such, the bezel housing and various other components of the handheld meter must be removed prior to replacing the valve. In addition, residual oil can remain in the valve cavity during valve replacement. The residual oil can migrate through the valve when the valve is reinstalled and can appear to the user as a new leak, even where there is no leak in the valve.
The fluid is dispensed out of the handheld meter through a nozzle. The nozzle includes an acetal seat on which a rounded, steel nozzle stem seats. The nozzle can experience leakage when contaminants are present in the fluid. In addition, the nozzle can experience fluid sputtering and/or stream fanning at high flow rates, and the nozzle can experience latent dripping of the fluid that remains in the nozzle tip when the nozzle stem shifts to the closed position.